function freureacalc(unitchoice,bun,urea,pcr,ucr){

var freurea=0;
creatinine=pcr;

//convert SI to US
if (unitchoice){
bun=bun/0.3651;
urea=urea/0.166;
pcr=pcr/88.4;
ucr=ucr/88.4;
}

//Fractional Excretion of Urea (FEUrea) = (SerumCr * UUrea ) / (SerumUrea x UCr) %

freurea= ((urea*pcr)/(bun*ucr))*100;


freurea=Math.round(freurea*100)/100;
	

return {
			freurea:freurea,
			creatinine:creatinine
		};		 
}



function ref(){
// display reference
 return "Fractional Excretion of Urea (FEUrea) = (SerumCr * UUrea ) / (SerumUrea x UCr) %" + "<br />In the setting of acute renal failure, a fractional excretion of urea >50 suggests ATN" +"<br />Carvounis CP, Nisar S, and Guro-Razuman S. Significance of the fractional excretion of urea in the differential diagnosis of acute renal failure. Kidney Int 62: 2223-9, 2002";

}